To make the vocals so much easier for males and females.

You can have a toggle centered at 0. If you shift it 100% to the right, you get female... if you shift 100% to the left, you get male.

You also have a (+) button to add more vocals (maybe 10 max, for now)

And the toggle is defaulted at the center.

That makes 2 vocals if you want to create an easy duet. If you want to add all 10 and mix them up between males and females, that can create an acapella group or opera or theatrical.

This would help with the gendered vocals and duets.